1. Field of the Invention
The present invention generally relates to a document processing apparatus and a document processing method and more particularly relates to a document processing apparatus and a document processing method for displaying a document having layout information in a display mode suitable for a screen, for example, on a mobile terminal.
2. Description of the Related Art
In patent document 1, a document processing apparatus which extracts and structures the contents of a print document and automatically inputs the structured contents into a computer is disclosed.
The document processing apparatus includes a layout analyzing unit configured to extract layout objects and a layout structure from a document image, a unit configured to extract logical objects based on typographic information obtained from character layout information of the document image, a unit configured to determine the reading order of layout objects and logical objects, a unit configured to extract hierarchical structure, reference structure, relational structure of logical objects as logical structures according to the reading order, and a unit configured to identify the structure of a multi-page document.
In a document search system disclosed in patent document 2, structures of documents are analyzed when creating a document database so that only corresponding portions of HTML documents that match a search condition are presented as search results. In this structure analysis, an HTML document is regarded as having three layers. The attribute of each document segment such as text or image is identified based on HTML tags, the relationship between an image segment and a text segment placed next to each other is evaluated, these segments are combined if they have a close relationship, and a header, which is identified based on HTML tags, and a segment under the header are combined.
A document image recognition apparatus is disclosed in patent document 3. The document image recognition apparatus extracts character areas and graphics/photo areas from an input document image obtained by scanning a print document, performs character recognition for the character areas, performs layout analysis, and generates a PostScript document or a HTML document which matches the input document image. In this layout analysis, titles and headings are also identified.
In a document image recognition method disclosed in patent document 4, the background color of a document image is identified, for example, by color clustering, pixels having colors other than the background color are combined to form connected components, and the connected components are classified into character areas and graphics/photo areas based on at least shape characteristics.
In an area dividing method disclosed in patent document 5, circumscribed rectangles of connected components of black pixels are extracted from an OR-compressed document image, the circumscribed rectangles are classified into characters and others based on their shapes and internal data, the circumscribed rectangles of characters are assembled into character lines and character areas, a histogram of the heights of the circumscribed rectangles of characters (the lengths of the sides which are perpendicular to the character line) is created, and a most common height of rectangles is used as the standard character size.    [Patent document 1] Japanese Patent Application Publication No. 11-250041    [Patent document 2] Japanese Patent Application Publication No. 2000-339347    [Patent document 3] Japanese Patent Application Publication No. 11-66196    [Patent document 4] Japanese Patent Application Publication No. 2001-297303    [Patent document 5] Japanese Patent Application Publication No. 7-73271
With the spread of the Internet and company LANs, technologies to deliver image data to terminal devices such as personal computers (hereafter called PCs) via networks are getting attention. For example, multifunction printers having functions, for example, of a printer, scanner, and image server are being used as image delivery apparatuses.
Also, the performance improvements of mobile terminals such as mobile phones and personal digital assistants (PDA) have made it possible to view document images on such mobile terminals. However, the displays of mobile terminals are normally small to give priority to portability and there has been a problem that the displayed document images are hard to read.
Most of such mobile terminals adopt a standard called QVGA with resolution of 320×240 pixels for their displays. However, for example, the size of an A4-size document image is around 3500×2500 pixels. If such document image data, for example, of a document shown in FIG. 15 is transmitted to a mobile terminal and the entire image is displayed as is on the terminal, the display size is reduced as shown in FIG. 29A. As a result, the characters in the image are blurred and become unreadable. If the display size of the image is increased to make the characters readable as shown in FIGS. 29B and 29C, a user must repeat vertical and horizontal scrolling many times to understand the entire contents.